Identification

Summary

The Opal-rumped Tanager is a medium sized species of the genus Tangara with a longer, thinner bill than most of species of Tangara. The plumage is predominately blue and black. The crown and back are black, with a bright opalescent rump. The head and underparts are deep iridescent blue (or the underparts are silvery blue in cyanomeleana). Contrasting with these colors are a reddish chestnut lower belly and crissum. Some of these colors are shared with close relatives such as the Opal-crowned Tanager (Tangara callophrys) and the Turquoise Tanager (Tangara mexicana).

Similar Species

A very similar species to the Opal-rumped Tanager is the Opal-crowned Tanager (Tangara callophrys); the distributions of these two species overlap in western Amazonia. Like the Opal-rumped Tanager, the Opal-crowned Tanager is characterized by a slender bill, predominantly blue plumage, and a bright yellow, opalescent rump. The two birds differ in that the Opal-crowned Tanager has a distinct opal crown and eyebrow as well as a black lower belly, rather than the distinctive chestnut lower belly of the Opal-rumped Tanager (Restall et al. 2007). Another similar species is the Turquoise Tanager (T. mexicana), which possesses similar plumage coloration, but which has a blue rump and a light yellow or white under belly (Ridgely and Tudor 1989, Hilty 2003). During field identification, the chestnut belly often is the easiest mark to distinguish the Opal-rumped Tanager from other similar species.

Vocalizations

Like many Tangara species, Opal-rumped Tanagers are not known for their song but they do have a distinctive call. Three kinds of vocalizations have been described in the literature. Common foraging calls are described as a series of rapid high pitched, thin, sit or siz notes repeated in bursts of two or three to form a series of six or more notes. The song is described as a weaker sequence of tiz notes that quickly rise and fall in pitch, e.g. tiz-tiz-tiz-ti’ti-ti-E’E-ti-ti-ti-tiz (Hilty 2003). A high-pitched twittering noise has also been observed during flight (Restall et al. 2007).

Nonvocal Sounds

None reported.

Detailed Description (appearance)

Adults: Sexes are similar in both size and plumage, but females have slightly duller coloration than males (Restall et al. 2007).

Adult, male: Tangara velia velia - Overall black and opalescent yellow on the dorsal side and deep blue-purple and chestnut on the ventral side. The bill is black, longer, and thinner than that of most Tangara species. The crown, nape, back, scapulars and tail are black. The chin, supercilium, auriculars and malar are bright cerulean blue while the throat is deep purplish-blue with an irregular black band across it. The rump is an opalescent straw yellow that becomes a greenish opal more distally before turning bluer on the uppertail coverts. Primaries, secondaries, and secondary coverts are black with deep purplish blue leading edges. The breast, sides, and flanks are purplish blue and the belly and undertail coverts are reddish chestnut (Restall et al. 2007).

Adult, female: Similar to the male, but tend to be duller and slightly paler than males (Restall et al. 2007).

Juvenile: Similar to females but the face is much darker (Restall et al. 2007).

The following statistics are comparative measurements of bill length, bill width, tail length, and wing-length between two differing groups of Opal-rumped Tanagers which may warrant separate species status: subpecies distributed in Amazonia (velia, signata, and iridina) and cyanomelaena of southeastern Brazil (Pinto de Assis et al. 2008):

Bill length (mm): Amazonian subspecies and cyanomelaena

Amazonian

Mean

SD

Min

Max

n

cyanomelaena

Mean

SD

Min

Max

n

Males

14.20

0.64

12.65

15.60

32

Males

16.18

0.78

15.00

17.10

12

Females

14.24

0.99

12.90

15.75

8

Females

15.32

0.73

14.20

16.50

7

Bill width (mm): Amazonian subspecies and cyanomelaena

Amazonian

Mean

SD

Min

Max

n

cyanomelaena

Mean

SD

Min

Max

n

Males

4.36

0.41

3.90

5.25

35

Males

4.73

0.30

4.20

5.25

13

Females

4.47

0.46

3.50

4.85

8

Females

4.74

0.30

4.15

5.00

7

Tail length (mm): Amazonian and cyanomelaena

Amazonian

Mean

SD

Min

Max

n

cyanomelaena

Mean

SD

Min

Max

n

Males

48.51

2.90

42.00

55.50

36

Males

52.54

1.95

49.00

56.0

13

Females

48.00

3.02

43.50

51.50

8

Females

50.13

2.54

45.50

54.0

7

Wing length (mm): Amazonian subspecies and cyanomelaena

Amazonian

Mean

SD

Min

Max

n

cyanomelaena

Mean

SD

Min

Max

n

Males

71.04

3.18

60.85

76.60

36

Males

72.42

1.93

69.50

70.80

13

Females

68.72

2.50

66.10

70.55

8

Females

69.42

1.92

66.50

71.55

8

Molts

In general, most tanagers only molt once a year (Isler and Isler 1987), and this prebasic molt likely occurs after the breeding season (Isler and Isler 1987, Ryder and Wolfe 2009). However, many species have been found to breed in subadult plumage (Isler and Isler 1987). In many species of Tangara, the preformative molt is partial (Ryder and Wolfe 2009). Species in the genus Tangara generally acquire adult plumage after the postjuvenile molt (Skutch 1954: 261). Although a subadult plumage is described for Tangara velia (Isler and Isler 1987), more specific information on molt and its timing is not available for this species.

Geographic Variation

There are 4 subspecies currently recognized (Clements et al. 2010):

T. v. velia - As described above as having black crown, back and tail with purplish-blue breast, face, and flight feather margins. Has straw-yellow opalescent rump and chestnut lower belly and undertail coverts (Restall et al. 2007). Ranges from the Guianas to the north bank of the Amazon River in Brazil (Storer 1970).

T. v. signata - Very similar to T. v. velia except for presence of greenish silver feathers on forecrown. Inhabits northeastern Brazil, south of the Amazon, in Para (Storer 1970).

T. v. cyanomeleana - The most differentiated plumage coloration from other subspecies. Breast is bright bluish gray (instead of bluish purple) and a has greenish silver, opalescent forecrown band similar to that of signata (Hellmayr 1936, Pinto de Assis et al. 2008 ). Allopatrically distributed from the other three subspecies; inhabits southeastern Brazil from Rio de Janiero to Pernambuco (Storer 1970).

Systematics

The Opal-rumped Tanager is classified in the genus Tangara, the largest genus of Neotropical birds. Tangara is divided into 13 species groups based on vocalizations, diet, geographic distributions, behavior, and appearance (Isler and Isler 1987). Isler and Isler (1987) placed T. velia in species group 13 with Tangara callophrys (Opal-crowned Tanager). These two species were formally classified together in a separate genus (Tangarella). Phylogenetic analysis of DNA sequence data confirms that these two species are sister taxa (Burns and Naoki 2004, Sedano and Burns 2010). In addition, these genetic studies showed that Tangara chilensis (Paradise Tanager), previously considered a member of species group 3, is closely related to the T. callophyrs/T. velia clade.

Due to its allopatric distribution and distinctive plumage, one of the subspecies of Tangara velia, cyanomelaena, may represent a distinct species (Ridgely and Tudor 1989, Pinto de Assis et al. 2008). In Pinto de Assis et al. (2008), comparative studies of morphological measurements and plumage color concluded that cyanomelaena should be treated as a separate species based on its diagnosability, unique plumage, and geographic isolation. No genetic data have addressed the specific status of this taxon. Although Sedano and Burns (2010) included two individuals of T. velia in their study, these were both from Amazonian populations and were shown to be less than 1% different in mtDNA sequence.